Capitalization - Carrying Amounts and Fair Values of Long-Term Debt (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Unamortized debt expense	$ 221	$ 222
Carrying Amount
Debt Instrument [Line Items]
Long-term debt (including current portion)	22,179	22,177
Fair Value
Debt Instrument [Line Items]
Long-term debt (including current portion)	20,101	20,525
CECONY | Subsidiaries
Debt Instrument [Line Items]
Unamortized debt discount	213	215
CECONY | Carrying Amount | Subsidiaries
Debt Instrument [Line Items]
Long-term debt (including current portion)	21,062	21,060
CECONY | Fair Value | Subsidiaries
Debt Instrument [Line Items]
Long-term debt (including current portion)	19,114	$ 19,517
Broken Bow II | Carrying Amount
Debt Instrument [Line Items]
Long-term debt (including current portion)	62
Broken Bow II | Fair Value
Debt Instrument [Line Items]
Long-term debt (including current portion)	$ 57